General trends, Group 17 and 18
- Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : ICl is more reactive than I_2.Reason (R) : I-Cl bond is weaker than I-I bond.In the light of the above statements, choose the mo… Answer: 2. Both (A) and (R) are correct and (R) is the correct explanation of (A) Key idea: interhalogen compounds are more reactive than th... 1
- Noble gases are named because of their inertness towards reactivity. Identify an incorrect statement about them. Answer: 2. Noble gases have very high melting and boiling points. Key idea: noble gases are monoatomic and held only by very weak dispersion... 1
- Match the Xenon compounds in Column - I with its structure in Column - II and assign the correct code :Column - I: (a) XeF_4 (b) XeF_6 (c) XeOF_4 (d) XeO_3Column - II: (i) pyramidal (ii) square planar (iii) distorted octahedral (iv) square pyramidalC… Answer: 2. (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i) (a) XeF₄ : square planar, (ii) (b) XeF₆ : distorted octahedral, (iii) (c) XeOF₄ : square p... 1
- The correct structure of tribromooctaoxide is : Answer: 1. (structure 1, see figure) Tribromooctaoxide is the neutral molecule Br₃O₈ with a Br-Br-Br chain. The figure shows the structure w... 1
- Which of the following statements is not true for halogens ? Answer: 2. All but fluorine show positive oxidation states. We need the statement that is NOT true for halogens. Option 1: Cl, Br, I and (as... 1
- Match the interhalogen compounds of column I with the geometry in column II and assign the correct code.Column I | Column II(a) XX' | (i) T-shape(b) XX_3' | (ii) Pentagonal bipyramidal(c) XX_5' | (iii) Linear(d) XX_7' | (iv) Square-pyramidal| (v) Tet… Answer: 1. (iii) (i) (iv) (ii) Key idea: use VSEPR for interhalogens. (a) XX': linear (iii) (b) XX₃' : T-shape (i) (3 bond pairs, 2 lone pai... 1
- HgCl_2 and I_2 both when dissolved in water containing I^- ions the pair of species formed is : Answer: 2. HgI₄²⁻, I₃^- Key idea: HgI₂ dissolves in excess I^- and I₂ dissolves in I^- by complex formation. HgCl₂ + 2I^-→ HgI₂ (red precipi... 1
- Which one of the following orders is correct for the bond dissociation enthalpy of halogen molecules ? Answer: 2. Cl₂ > Br₂ > F₂ > I₂ Key idea: bond dissociation enthalpy generally falls down group 17 (bigger atoms, longer bonds), but F₂ is un... 1
- Among the following, the correct order of acidity is : Answer: 2. HClO < HClO₂ < HClO₃ < HClO₄ Key idea: in oxoacids of the same halogen, acidity rises with the number of oxygen atoms (higher oxi... 1